Abstract: Seven subjects participated in a two-part study to evaluate mouth alcohol dissipation in alcohol positive subjects. In part one, subjects rinsed their mouths with a vodka solution and were breath tested after 1, 2, 3, 4, and 5 min intervals. On average, breath alcohol concentration (BrAC) decreased 20.4% (range 3.2–47.9%) between 1 and 2 min after rinsing. In part two of the study, multiple breath tests were administered after rinsing once with the vodka solution. The BrAC decreased more than 0.020 g/210 L between the first and second tests for all subjects (average 0.095 g/210 L, range 0.021–0.162 g/210 L). The average time for subjects to reach their unbiased BrAC was 9.35 min (range 4–13 min) after rinsing. This study reaffirms the need for duplicate breath testing and confirms that the minimum of a 15-min observation period is sufficient for mouth alcohol to dissipate in alcohol positive subjects.